Depending on the end use of a coating composition in automotive applications, such as that applied over an auto body versus that applied over a car bumper, the metallic gloss provided by flakes is typically adjusted by adding additives to the composition, such as flatteners to reduce the gloss. The higher the amount of flattener in a coating composition, the lower will be the metallic gloss of a coating resulting therefrom and vice versa. Thus, paint manufacturer typically checks a sample of a coating composition, such as automotive OEM paint or refinish paint, while it is being made to determine the metallic gloss of a coating that would result from it. Therefore, from time to time, an aliquot of such coating compositions being manufactured is taken, applied as a layer of desired thickness over a test substrate, dried and/or cured into a coating and its gloss measured to check whether the gloss is in a desired gloss range. The process parameters are then adjusted and the aforedescribed testing procedure is repeated until the adjusted coating composition falls within a desired gloss range.
The aforementioned testing procedure is not only time consuming and cumbersome but it also results in frequent interruptions in the manufacturing process. As a result, the batch-to-batch quality of the resulting coating compositions can be detrimentally affected. Therefore, a need exists to develop a process that could predict the gloss of a coating that would result from a coating composition while it is still being manufactured such that the manufacturing process could be readily adjusted on a real time basis to get the desired metallic gloss.